As of March 2019, you can now replicate your VMWare virtual machines and physical servers directly to managed disks within Azure

In the past, when you deployed ASR you would have created a storage account when configuring replication. You’ll find this option is no longer available, as the data is now replicated to Azure Managed disks. The type of managed disk you select would depend on data change rate on your source disk.

What about virtual machines which were configured to replicate to a storage account in the past?
These storage accounts will still exist and your VM’s will continue to replicate to storage accounts

What is the benefit of Azure Managed disks?
You don’t need to track and manage multiple target storage accounts anymore. Azure Managed Disk will create the replica disks at the time of enabling replication. An Azure Managed Disk is created for every virtual machine disk at on premises and managed by Azure

What if I select standard managed disks but decide that I need to upgrade to premium?
You can switch to your required managed disk without disabling and enabling replication. However, once you change the Managed Disk type, please be sure that you wait for fresh recovery points to be generated if you need to do test failover or failover post this activity.